Computers based patient simulations have been recognized as a valuable tool in medical education. With the advance of the Internet, the development of Web-based case simulations and their integration into the curriculum has become possible. World-Wide Web (WWW)-based, interactive, multimedia case simulations may improve students and health care professional clinical knowledge and skills and may result in improved proficiency in the interaction with patients. The goal of this research is the development an interactive, multimedia WWW - based case simulation. The simulation will capture a sufficient number of features that determine an actual clinical encounter to allow a metamorphosis of the user's mind into that of a physician interacting with a patient (verisimilitude). An evaluation tool based on the principles of decision analysis will aid students by reviewing their mistakes, identifying areas of weakness and aiding in the development of a clinical decision model. Using findings and libraries from the first case simulation, we will develop an authoring tool, that will allow physicians to add new cases to a case simulation library on the Internet. We will continuously monitor user demographics, pattern of use, objectives and subjective impact. To evaluate the impacts of computer case simulation on student's performance, we will randomize students to standard educational materials or to the computer simulation. An encounter with a standardized patient simulating a problem similar to the computer simulation would provide the outcome measures in terms of diagnostic accuracy, work-up propriety, and international propriety. The development of a case simulation and evaluation tool accessible on the Web in conjunction with the verification of its acceptance and effectiveness on the user's clinical skills will allow the integration of Web-based case simulations into medical school curricula worldwide.